[fusion-users] Legend widget speed issues

[Anders Selberg]

Hello everybody,

We experience issues with the legend widget and would like to hear from you
more experienced Fusion programmers on this:

If the user checks/unchecks several layers after each other, the updating
process doesn’t seem to be able to keep up. It appears as if the calls
interrupt each other, and then when the map image is loaded the layers shown
in the map aren’t the same ones as those checked. I’m not sure whether it is
the javascript that gets interrupted or the server calls, if I use Firebug
to step through it, the process is slowed down enough to avoid the
problem…(The ajax viewer doesn’t appear to have these issues btw, but maybe
they aren’t really comparable?)

Still, I managed to solve this by letting stateChanged() push the clicked
layers onto a queue. For the first layer in the queue I first do an
obj.show(true), then call a custom php that explicitly sets the visibility
with $myLayer->SetVisible(true/false). On the callback from this, first I
call a slightly modified drawMap2(), that requests the map image after first
nulling the show/hidelayers/groups-arrays, and then I continue shifting the
queue, repeating the procedure. This makes the legend much more robust,
although noticeably slower. The map image requests from drawMap2 get
interrupted all the time but that’s all right, since the visibility is
already set, and the final layer’s request doesn't.

I’m not sure what implications this might have on the rest of the code, and
it’s kind of ugly too I guess. So I wonder if you know a better way to
handle this.

(Using Fusion 1.1.1 and MGOS 2.0.2)


Regards,

Anders

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